When off pumping gets it stiff but when turned on the pedal travels all the way down. I was originally wondering about the booster but from what I have read it seems to be OK. Also there is a hissing noise but it is not constant when depressed as in a leak in the booster. It is only while moving the pedal. I was thinking maybe the master cylinder but I'm no brake expert. I was wondering if I could plug the 2 ports one at a time with something like this in order to rule out anything beyond the master cylinder on each port. https://www.oreillyauto.com/detail/c...der+plug&pos=1